Three Dimensional (3D) video is one of the lesser understood forms of video making in present times. The first work on 3D stereoscopy dates back to 1838 when Charles Wheatstone showed that the difference in the left and right images, as viewed by each eye of a viewer is interpreted by brain as a three dimensional image. When we see the world around us with our two eyes, we experience binocular stereopsis. It is the ability of our brain to combine two images of slightly different perspective that enables us to perceive depth. Depending on the differences in apparent position of objects within the two images, some of the objects appear closer than others.
The conventional form of stereoscopy is to use two 2D (two dimensional) images with each providing a different perspective to the brain. A slight change in perspective in horizontal direction allows the brain of a viewer to perceive depth. The horizontal difference between the two 2D images i.e. the left and right views is called disparity. Disparity is a very important cue in the perceived spatial depth of the object in stereoscopic vision.
To view the stereoscopic 3D video the viewer usually has to wear 3D glasses to filter a different image to each eye. Autostereoscopic displays use the angular separation of the viewers eyes to project a different image to each eye of a viewer and hence these do not require glasses for the 3D effect. In autostereoscopic displays for multiple viewers, several views are used to generate the 3D video allowing more flexibility in viewing angle thus enabling multiple viewers to watch the 3D video.
Apart from the advances in display technologies in 3D video, work is also carried out to standardize coding schemes for multiview 3D. Multiview Video Coding (MVC) enables efficient encoding of sequences captured from multiple cameras and on the receiver end additional intermediate views can be synthesized for free viewpoint TV. In all, a lot of work is being put in 3D video, so that viewers can use 3D video in different applications. On the other hand there has not been much work done to evaluate the quality of 3D video being produced from different displays.
Evaluation of 2D video data can be done based on subjective or objective tests. In subjective test several viewers are shown the test video and are asked to rate it on a scale. The process of subjectively evaluating the quality of a video is expensive and time consuming. In contrast objective tests can be performed by a computer and hence are easier and less costly. Still, accurate subjective tests are used as a benchmark for the evaluation of objective tests. There are many objective methods available which can be used to evaluate the quality of 2D video with high accuracy. In case of 3D video there is lack of research both in terms of subjective tests and on objective methods.